Remove erroneous logging around pt.*Error calls
legacy/trac#31794 (moved) added logging around every function call that returns an
error type; but this is the wrong thing to do in the case of functions like pt.CmethodError, pt.SmethodError, and pt.ProxyError. These functions are called for their side effect of sending a PT error message on stdout; it happens that they also return a representation of the error message as an
error object for the caller to use if it wishes. They always return a non-
error object; a non-
nil error is not an exceptional event to be logged.